Improving case detection through TB contact risk stratification by Xpert MTB/RIF Ultra and spatial parameters. Evaluation of an innovative ACF strategy in Mozambique.

Prompt diagnosis is critical for tuberculosis (TB) control, as it enables early treatment which in turn, reduces transmission and improves treatment outcomes. We aimed to determine the impact of the scale-up of Xpert Ultra as frontline test for TB diagnosis, and an innovative active-case finding (ACF) strategy (based on Xpert Ultra semi quantitative results and spatial parameters) on new TB cases diagnosed in a semi-rural district of Southern Mozambique. From January-December 2018 we recruited all incident TB-cases (index cases, ICs) and their household contacts (HCs). Community contacts (CCs) recruitment depended on the semi-quantitative results of Xpert Ultra of the IC and the population density of the area where the IC lived in. TB-contacts, either symptomatic or people living with HIV (regardless of symptoms), were asked for providing a spot sputum for lab-testing. Trends on TB case notification in the intervention area were compared to the previous years and to those of two districts in the south of the Maputo province (control area) using an interrupted time series analysis with and without control (CITS/ITS). A total of 1010 TB ICs (37.2% laboratory-confirmed) were recruited; 3165 HC and 4730 CC were screened for TB. Eighty-nine additional TB cases were identified through the ACF intervention (52.8% laboratory-confirmed). The ACF intervention increased by 8.2% all forms of TB cases detected in 2018. CITS model showed an increase of laboratory confirmed TB cases in the intervention district, compared to the control area. Xpert Ultra trace positive results accounted for a high proportion of laboratory confirmations in the ACF cohort (51.1% vs 13.7% of those passively diagnosed). Number needed to screen (NNS) to find a TB case differed widely among HCs (NNS:55) and CCs (153). The intervention resulted in an overall increase in TB diagnoses and higher proportion of laboratory confirmation.